The broad, long-term objective of this application is to perform autoantibody profiling utilizing protein and peptide autoantigen microarrays to predict, design, and guide the selection of tolerizing therapy in the prevention of systemic autoimmunity. We have reduced to practice the use of large-scale arrays to identify autoantibody profiles in many human autoimmune diseases. As a first step toward the development of antigen- or tissue-specific tolerizing agents, we will reproduce these studies using serum derived from several animal models of human autoimmune diseases, including collagen-induced arthritis (CIA), experimental autoimmune encephalomyelitis (EAE), and the non-obese murine model of diabetes. Using serum and tissue samples provided by our co-investigators, we will determine whether autoantibody profiling might prove useful in guiding the choice of therapeutic agent or providing surrogate markers of successful intervention. We predict that autoantibody profiling will allow Dr. Steinman to design individualized tolerizing therapies that employ naked DNA vaccination. Autoantibody profiling will also be employed in evaluating the therapeutic response in the gene therapy trials proposed by Drs. Fathman and Bluestone. We will use biochemical, immunological, and molecular biological techniques to validate and extend our ongoing protein array platform in exploring four specific aims of this application: (i.) to extend current studies employing protein and peptide auto antigen microarrays in EAE; (ii.) to develop and validate the use of protein and peptide autoantigen microarrays in several rodent models of RA; (iii.) to develop and validate the use of protein and peptide autoantigen microarrays in the NOD mouse model of insulin- dependent diabetes mellitus (IDDM); (iv.) to determine whether the autoantibody profile determined using microarrays is a valid tool for guiding the selection of a preventive therapy, or to predict the response to therapy, in the rodent models described above. The results of this application may elucidate an expanded role for B lymphocytes in autoimmunity, heralding an era of customized, antigen- or tissue-specific tolerizing therapy in humans.